Crawl space

Northern Iowa...So wife wants to attach house to garage, 7'x16'. Brick house. Plan to set posts 7' out from house and run joists from beam to ledger boards. Problem is, I only have 7 to 11 inches between floor level of back door and ground/sidewalk. I can sandwich 2/3 2x4s to make joists but with the beam, flooring, joists, etc. I am getting pretty close to the ground. Will use ground contact lumber and regular treated where needed, but need some ideas on how to mitigate any moisture in such a small area, How to insulate the walls or floor....or any other ideas...
Thanks!

may come to that but don't want to...cold floors, don't like in floor heat and associated problems, floating slab inside a post/beam construction... thanks for the thought, like i say, might come to that.